Prokaryotic Cell Structures 1

by Jason Amores Sumpter
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hi in this video will be taking a look at pro carry its, which can be broken up into bacteria and archaea. Now, pro carry attic cells are significantly smaller than eukaryotic cells. And what differentiates them mainly from eukaryotic cells is that they lack a nucleus, and they lack membrane bound organelles. Now, as you can see in this diagram of a pro carry attic sell here, uh, the central region of the cell contains the nuclear oId, which is basically just condensed ball of most or all of the DNA that the organism contains now pro carry. It's also contain what are called plasmas, which are small molecules of DNA that are extra chromosome away, as in separate from the chromosome of cell. So you can see right here this is our nuclear Lloyd, and over here we have these little plasmids. Now you might recall that pro Kerasiotes have circular, double stranded DNA. Unlike you, Kerasiotes like us who have linear DNA now additionally pro carry. It's have a cell wall that's made of peptic like hand, and that's what gives the cells. They're shaped this rigid outer wall that you see here in red. That's what's going to give pro carry attic cells their shape. And again, um, this is in part because, unlike eukaryotic cells, which have a site of skeleton to maintain rigidity, uh, this cell wall is there, Thio, um, keep the cell from collapsing in on itself and and to maintain the proper structure Now, peptic Google I can is something we discussed way back when we talked about biological molecules. And you might recall that it is comprised of proteins that's the kept it apart and also carbohydrates. That's the Glick and component. And basically, what you have are these sugar chains, which I'm marking here in blue. These are sugar chains, right? That's our carbohydrate. And then we also have these little, uh, little peptides. You can see they're not very big there. Only a few amino acids long, right? So these are our peptides. And as the figure points out, technically these air illegal peptides and that determination comes from the number of amino acids in the chain. But that's really getting into the realm of biochemistry. You guys don't need to worry about that. All you really need to know about peptic, like in is that it's thes sugar chains that air Cross linked cross linked by a small peptides and that cross linking is what makes what makes thes cell walls so strong, right, this peptic like and this is a strong, resilient material. Now, not all bacterial cells have so or have, um, exterior structures that are similar. In fact, there's there's kind of, ah divide in bacteria, and it's based on the sustaining technique called the gram stain. So before we get into what the difference between Gram positive and gram negative bacteria is, I just want to point out that, um, this is a distinction defined by a test from a long time ago, right? So, uh, this microbiologist whose name was Graham that's where the name came from Name comes from came up with this staining technique, which uses, actually a variety of different stains. We're not going to get into the specifics of how it works, but eso don't You know, I point that out because don't think that the gram stain is actually just one stain. It's a type of technique that involves many stains and washing the cells and then applying new stains. It's actually a you know, kind of ah, longer procedure than this name implies. And essentially there's a pigment used right, a dye used that will be absorbed by peptide of like in. So essentially, this staining technique allows people to observe pep to dig like an in the cell walls of precarious oats. And, you know, this is they're looking through microscopes, of course, to see the cells. So basically some bacteria which have been dubbed gram positive bacteria because they have a positive test in there, they have a positive result in the gram stain. And that is because they have this thick kept it. A Gleicher hand layer, right could see this thick outer layer of peptic like. And so when the gram stain technique is done to these cells, lots of this particular stain called crystal Violet um is going to be absorbed into this thick layer of peptic like and so these cells are going to have a strong purple appearance due to that crystal violet stain. Now, gram negative bacteria actually have this outer membrane of Lippo. Polly Sacha rides. And let's pause there. What do you think? Lippo? Polly, Sacha rides are well, Lippo, right? That's gonna be lipid, right? and then Polly Sack rides. So it's, um, you know, again sugar chains with lipid attachments. So, um, again, just always be thinking about your prefixes and suffixes when you hear these biochemical names because they'll often reveal what it is we're talking about. So anyways, gram negative bacteria have this outer membrane of lipid Polly sack lipid Polly Sacha rides and then inside that they actually have this thin layer of peptic glikin. Right? So here's our peptic like an right. It's just this thin little layer. Our outer membrane may actually jump out of the image here. All right, outer membrane you can see marked here in green, that dark green color that is made up of lipid Polly Sack, Lippo, Polly, Sacha rides. And then, of course, we have the plasma membrane, this light green interior structure, right, and this blue light blue space that you see between the Pepto Google I can layer and the plasma membrane as well as the outer membrane that's actually called the Perry Plaza Mick space. And this is literally like a gap between these coatings of the cells of speak. Um, and it's actually super important for the realm of microbiology. We're not gonna get into it in our discussion. Just pointing out that there is a little little space there and you can see that in gram positive bacteria. They have just one of those little spaces because they don't have that outer membrane layer anyways. So, uh, this is a distinction often used to characterize bacteria. Are the gram negative? Are they gram positive? And really, it's just referring thio, uh, sort of how the cell organizes its outer structures, right. Do they have this thick, outer peptic like handler? Or do they have a little faith thinner, internal peptic like antler with this outer Lippo Polly Sacha ride membrane. And again, this is not a distinction. Um, you know, born out of how out of, you know, some bad, you know, evolutionary trend. This this is a distinction that is based upon a laboratory test called the Gram stain. So with that, let's flip the page